U.S. Pat. No. 5,213,123 to John Whitfield disclosed a flat top umbrella comprising a foldable frame and a web provided having a substantially circular central portion and a substantially annular skirt portion continuous with the central portion.
However, such a conventional flat top umbrella has the following drawbacks:
1. The frame assembly (22) for fastening the web (20) consists of many ribs, stretcher arms, coupling members and tensile elements, thereby increasing the assembly complexity and production cost. PA1 2. The elongate ribs 34 should be strong enough to support the web and the umbrella structure. If the ribs 34 are made of steel material as popularly used in a conventional umbrella, the whole umbrella will be very heavy since there may be twenty-one ribs 34 in practical production, thereby being heavy, clumsy and inconvenient for carrying purpose. PA1 3. The tensile elements (46) and string-like elements (47) as provided in the frame assembly (22) may tangle or influence the folding or unfolding operation of the umbrella. PA1 4. No restoring mechanism is provided to facilitate the folding of an opened umbrella, causing a slow folding action when closing the umbrella from an opened state.
The present inventor has found the drawbacks of the conventional flat top umbrella and invented the simplified flat top umbrella having a light compact rib assembly.